1. Field of the Invention
This invention relates to a reusable sealed coupling for joining two pipes and more particularly it relates to a reusable sealed coupling for coupling together a vent pipe and an inducer housing in a temperature control apparatus, such as a furnace.
2. Description of the Prior Art
There are numerous applications in which two pipes must be joined together in such a manner as to create a tightly sealed connection. Prior art has addressed this goal for a number of different applications, as, for example U.S. Pat. No. 3,913,955 to Teja for a coupling for vehicle exhaust pipes, U.S. Pat. No. 2,165,920 to Burnip for the joining of sewer pipes and U.S. Pat. No. 4,056,273 to Cassel for pipes in vehicle exhaust systems. None of these resemble the instant invention.
Gas furnaces typically include a primary heat exchanger positioned adjacent a burner box containing burners. During operation of the furnace, a blower moves circulating air over the heat exchanger to produce heated air that is directed to a desired location. Gas is supplied to the burner box by a gas manifold having orifices that direct the gas into the burners. The gas exiting the burners is ignited by an ignitor provided in the burner box. The burners allow combustion of the gas as well as direct heated flue gas into the heat exchanger. The typical heat exchanger includes cells with a channel or pass formed in each cell to direct the flow of flue gas produced by combustion. These cells are positioned side by side in a parallel manner and are provided with a predetermined spacing to allow the blower air to flow around the cells. The blower air is thus heated by convection as it circulates over the cells.
A sheet metal panel or cell panel having burner target plates is typically provided to position the burner box relative to the inlet side of the cells contained in the heat exchanger. An inducer having a motor and fan is typically mounted on the discharge side of the heat exchanger. The inducer is activated to induce a flow of flue gas through the heat exchanger and into vent piping so that the flue gas may be vented to a location exterior to the furnace.
The residential heating industry has advanced with the advent of condensing gas furnaces. These furnaces typically included a primary heat exchanger as well as a condensing heat exchanger. A blower in these condensing furnaces similarly provides circulating air flow over both heat exchangers to produce heated air that may be directed to a desired location by a system of duct-work and registers.
In such condensing furnaces, both the primary heat exchanger and the condensing heat exchanger include cells with a channel or pass formed therein to direct the flow of flue gas produced by combustion. These cells in both the primary and secondary heat exchangers are positioned side by side in a parallel manner and are provided with a predetermined spacing to allow blower air to flow around both groups of heat exchanger cells. Gas is similarly provided to the condensing furnace by a gas manifold having orifices that direct the gas into burners contained in a burner box. The burner box is secured to the inlet side of the primary heat exchanger to align the discharge end of the burners with the inlet ports of the primary heat exchanger cells. The gas is ignited by an ignitor as it exits the burners contained in the burner box. The heated flue gas produced by combustion is then directed into the primary heat exchanger cells.
The condensing heat exchanger of the furnace is configured in a similar manner to its primary heat exchanger. A series of side by side condensing cells is provided. Each of these condensing cells has an inlet port for receiving flue gas discharged from the primary heat exchanger. The inlet ports of the condensing heat exchanger cells are aligned and secured in a sheet metal panel forming the inlet side of the condensing heat exchanger. The inlet side of the condensing heat exchanger is fluidly connected to the discharge side of the primary heat exchanger by a coupling box. The condensing cells function to exchange heat with the clean circulation air and to condense water vapor out of the products of combustion contained in the flue gas. This condensate drains from the condensing cells into a collector box provided on the discharge side of the condensing heat exchanger. The collector box extends through the cell panel below the burner box and includes tubing to further drain the condensate from the box into drain piping. The collector box is provided with an opening to which the intake side of an inducer in fluidly secured. The inducer in the condensing furnace induces the flow of heated flue gas through the cells in both the primary and condensing heat exchangers.
With recent advancements in the art, a commercially feasible condensing gas furnace having four possible installation orientations has been proposed by the assignee of the present invention. Such gas-fired furnaces are known in the art as multi-poise condensing furnaces and are disclosed, for example, in the copending, commonly assigned U.S. patent application Ser. No. 08/089697, entitled "Multi-Poised Condensing Furnace". These multi-poise furnaces are installable with either an upflow, downflow, horizontal-right flow, or horizontal-left flow orientation. They include design features which allow the furnace to function properly and just as efficiently in any one of these four possible installation orientations. One such feature results in proper drainage of condensate from the condensing heat exchanger cells into the collector box irrespective of the selected installation orientation. To accommodate the multi-poise furnace, the inducer employed therein features two optional discharge ports. Depending on the installation orientation, one of the two inducer discharge ports is selected to be connected to the vent piping while the other unused port is capped with an air-tight seal. Because the installation must sometimes carried out on-site without prior knowledge as to which orientation is appropriate, connection of one discharge ports in the inducer housing to the vent pipe will sometimes have to be performed in the field.
The prior art in furnace systems has relied on coupling two pipes together using two hose clamps, with each pipe being clamped to a different section of the coupler. This provided a seal against leakage of flue gas and/or condensate, as well as some degree of rigidity between the two pipes (which could be of differing sizes). Hose clamps are expensive, however, and may be subject to fatigue in those instances when they are repeatedly tightened and released. More importantly, for furnace, as well as other applications, it is desirable that a high degree of rigidity be maintained along the two pipes. It is also desired to provide a form of coupling to be used between a vent pipe and an inducer housing that would be reusable and that would be inexpensive to produce and relatively easy to install and maintain.